Ellsberg, who became one of the first to be prosecuted under the 1917 Espionage Act, told CNN that if he had been in Snowden's position, he would have broken the law in an act of civil disobedience.

"I'm very impressed by what I've heard in the last couple of hours including Snowden's own video here," Ellsberg told the network Sunday night. "I think he's done an enormous service — incalculable service. It can't be overestimated to this democracy. It gives us a chance, I think, from drawing back from the total surveillance state that we could say we're in process of becoming, I'm afraid we have become. That's what he's revealed."

Ellsberg said one thing that is clear is that Snowden broke the law. It's a position, Ellsberg knows well. As we wrote back in 2011, Ellsberg said when he saw the leaked Pentagon Papers appear in newspapers, he thought he would spend the rest of his life in prison. The documents revealed government deception as they were building their case to go to war with Vietnam.

Ellsberg went to trial but the charges against him were dismissed when the judge found evidence the Nixon White House "had agents break into the office of Ellsberg's psychiatrist in a search for ways to discredit him."

Ellsberg said that from what he's heard about Snowden, the 29-year-old is willing — like he was — to give up his life for the good of the country.

But Ellsberg wonders if it could really be a crime for someone to expose a practice he says violates the constitution.